The present invention relates to an eyeglass lens grinding apparatus for grinding a pair of eyeglass lenses such that they conform to the shape of an eyeglass frame.
An eyeglass lens grinding apparatus is known that automatically performs all steps in the grinding process up to the bevelling stage on the basis of the processing information that is determined from the data of measurement for the shape of an eyeglass frame, layout data and the like to process the peripheral edge of an eyeglass lens.
This apparatus has the advantage that processing of the lens to conform to the shape of an eyeglass can be easily accomplished by merely entering the necessary data. Yet, glass and other lenses that do not have very high processability may sometimes fail to be processed with satisfactory precision on account of the mechanical rigidity of the apparatus. To deal with this problem, the processed lens is fitted into the eyeglass frame to see if it has the correct size and, if not, the second grinding, commonly called "double grinding", is performed to achieve a fine adjustment of the lens size (corrective processing).
In the double grinding, only the lens size is corrected on the basis of the information provided by preceding finishing step and the lens is subjected to another finishing step. This means that if an eyeglass lens for the right eye has been first processed, it must be fitted into the eyeglass frame to see if it has the correct size and, if not, it must be subjected to double grinding before processing of the lens for the left eye can be started. In other words, the lens for the left eye cannot be processed until after the checking of the size of the lens for the right eye (and its corrective processing if this is necessary) is complete and this has lowered the overall efficiency of the grinding operation.